WHAT IS POTASSIUM METABISULPHITE?

Potassium Metabisulphite is an inorganic chemical compound with low toxicity. It has its other names as potassium pyrosulphate and Dipotassium disulfite. This potassium salt is a food preservative that preserves the natural color of food and protects against bacteria. It is freely soluble in water.

Potassium Metabisulphite appears as a white powdery solid. It has a monoclinic crystalline structure with a sharp/pungent odor of sulfur dioxide. It decomposes at 150 to 190°C and emits toxic fumes of Sulphur dioxide and potassium sulfate.  In the presence of moisture in the air, it oxidizes to the sulfate, more rapidly. It is not soluble in alcohol as well as ethanol. It reacts with acid solution readily due to its acidic nature. When it is mixed with water, it is a corrosive acid.

Potassium Metabisulphite has many applications across the food, textile, metal, and film industries. Some of these uses include, as given below;

• It is used for preserving lemon juice and pickles.
• It serves as a stabilizer in the brewing industry to inhibit the growth of wild bacteria and fungi
• It is used for preserving fruits as part of the dehydration process.
• It preserves the taste of dehydrated foods to make them palatable.
• It acts as a bleaching agent in coconut cream.
• It is utilized in the neutralizing monochloramine from tap water.
• It serves in dyeing and printing for textiles.
• It helps precipitate gold from the solution in aqua regia.
• It works in developing solutions for photographs.
• It functions as an antioxidant, in winemaking.
• It works as an antiseptic reagent, a reducing agent, and is a source of sulfurous acid.

Potassium metabisulphite is stored at a maximum temperature of 25 °C its shelf life is 6 months. It does not burn itself and is thus a non-flammable salt. It reacts explosively with strong oxidizing agents.

Potassium metabisulphite is prepared by treating a solution of potassium hydroxide with sulfur dioxide.